Breeding

Double Trouble, Part II

Twins pose a difficult challenge to dam, foal and owner alike; find out the best way to avoid having "double trouble."

This article is a continuation of last Friday’s article on the difficulties posed by twin foals.

Conformation Crisis

Another financial burden twins impose on their owners is the cost of correcting their deformities. Kate Streifel of Hawley, Minnesota, owns a mare who carried twins full term in 1991. Dakota Michelle, or “Mikki,” birthed a colt and a filly, “Cody” and “Jenny.” Cody was smaller than most newborn foals, and Jenny was even smaller than him.

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Jenny was so small, she had difficulty reaching her mother’s udder to nurse. At 2 days of age, Jenny’s front legs began to bow out, and it was apparent her knees were not fusing correctly. Kate’s veterinarian tried to supplement Mikki with calcium to correct Jenny’s deformity, but that did not succeed. The filly was taken into surgery to correct the problem, but she was too weak and died on the operating table. It was later discovered the filly also had a heart murmur. Gary and Charlene Wickwar of Goodland, Kansas, experienced a similar, but less severe problem, when their mare, Alamitos Lolly, birthed twin colts in the spring of 2007. The colts were blessed with gleaming colors, a bay roan and buckskin, but they were also hindered with angular deformities in their front legs. Luckily, the Wickwars’ colts’ legs straightened without surgery. While singleton foals can be born with contracted tendons, Dr. Espy says the lack of space inside the uterus makes twins more likely to have contracted tendons. Twin foals are more susceptible to abnormalities, including but not limited to, seizures, organ disfunction, improper conformation and respiratory disorders. Twins are also more susceptible to being “dummy” foals, which lack a nursing instinct and have a loss of some of their mental capacity due to trauma during foaling or a lack of oxygen. Some dummy foals will recover, but twins have a greater chance of being handicapped their entire lives. Twins are also prone to failed passive transport, which means antibodies are not absorbed from the dam’s colostrum and must be acquired by some other means. 

The Solution

Fortunately for Quarter Horse owners, twins only occur in 5 to 10 percent of Quarter Horse mares. This is a much lower percentage than several other breeds, including the most susceptible, Thoroughbreds, which will double-ovulate 20 to 30 percent of the time. Unfortunately, there is no way to prevent a mare from conceiving twins. Dr. Espy says double ovulation is not genetic, can’t be avoided by nutritional adjustments and doesn’t correspond with the mare’s age. The only way to ensure a single pregnancy is to sonogram (ultrasound) early and prevent twins from developing. Although twins can go undetected even in mares that have ultrasound scans, Dr. Espy says human error is to blame. Sperm can stay alive inside a mare for as long as seven days. This means if the mare releases two eggs, the foals can be conceived at different times. Embryos can’t be detected until they are 12 days old, therefore if the mare is examined too early, a younger embryo may be missed. Dr. Espy says it is critical to know the exact date your mare was bred and do an ultrasound scan as close to Day 16 as possible. Veterinarians recommend that mares be checked 14 to 16 days after ovulation. The embryos will be mobile inside the mare’s uterus up to Day 16. On Day 17, embryos will develop a sticky surface and attach to each other, as well as to the uterine wall. This makes it much more difficult to reduce the smaller of the two embryos without aborting both. Because the twins tend to attach to each other, they are primarily found in the same uterine horn. Dr. Espy says when he aborts foals in the same uterine horn, he separates the twins during a rectal ultrasound and rubs the smaller embryo with the ultrasound probe by pressing it between the probe and the mare’s pelvis or the probe and his finger. The aborted embryo will be absorbed, and the remaining foal will have a better chance of developing normally. On Day 16, the embryos are only a half-inch long and do not develop brain or organ function until Day 42. So there is no concern for pain to the fetus.

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“Usually the mare will reduce one twin on her own, but you can’t rely on that,” Dr. Espy says.

Learning From Experience

Kate’s mare, Mikki, had three successful single-foal pregnancies after her twins. Gary and Charlene continue to take precautions to ensure their mares only have one foal each season, but decided to retire "Lolly" from the broodmare band after she raised the twins.